Historically postage meters have been mechanical and electromechanical devices that: maintain through mechanical or "electronic registers" (postal security devices) an account of all postage printed and the remaining balance of prepaid postage; and print postage postmarks (indicia) that are accepted by the postal service as evidence of the prepayment of postage. With the introduction of postage meters that print a postal indicia by means of digital printing it became possible to print slogans and advertising material in the vicinity of the postal indicia.
The United States Postal Service currently handles large volumes of normal mail, i.e., first class mail, second class mail and third class mail. However when it comes to specialty mail, i.e., priority mail, certified mail and registered mail, the United States Postal Service uses gummed service stickers, and forms to indicate and process the specialty mail. The unnecessary use of gummed service stickers and completion of forms by hand is time consuming, error prone and hence raises the expense for receiving these services. Furthermore, the use of some services, i.e., certified mail requires the mailer to physically deliver the mail piece to the post.